Electric crucible



June 20, 1944. BLACK HAL 2,351,594

ELECTRIC CRUCIBLE Filed Aug. 51, 1942 14 Lawrence F. Black Clarence H. Mel/0r which functions as an electrode.

Patented June 20, 1944 ELECTRIC GRUCIBLE Lawrence F. Black and Clarence H. Mellor,

' Denver, 0010.

Application August 31, 1942, Serial No. 456,755

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without payment to me of any royalty thereon,

This invention relates generally to electrical heating devices but more particularly'to an electrically heated crucible for the melting of metals.

One object of the invention is to provide a safe and efllcient crucible, highly resistant to heat, and one which is inexpensive to manufacture.

Another object of the invention is to provide a crucible of the type described which is formed of non-fusible members, and one which is easy to operate.

Another object of the invention is to provide a crucible which is of simple and rugged construction, easily assembled, and unlikely to get out of order.

With the foregoing and other objects in view, which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of invention herein disclosed can be made within the scope of what is claimed without departing from the spirit of the invention.

Fig. 1 is a perspective view of the crucible showing its electrical connections to a source of power through a transformer;

Fig. 2 is a sectionalized view of the crucible taken on a central vertical plane:

Fig, 3 is a combined sectionalized and diagrammatic view of the cup assembly and the electrical connections to the source of power.

Referring to the drawing, in which like parts are represented by similar reference characters, the numeral l indicates a cylindrical carbon cup The cup is formed at its upper extremity with a hemispherical concavity H which extends almost to the outer surface of the cylinder, forming a circular rim which is indented and extended in one place to provide a pouring spout. The inner wall of the carbon cylinder forms a circular opening or passag l2 in which is fitted a. tubular member or sleeve I3 formed of asbestos or other suitable insulating material. The upper extremity of the tubular member l3 terminates at its intersection with the inner concave surface ll of the cup. The lower extremity of the tube I3 projects a slight distance below the flat lower surface of the cup. Within the asbestos tubular member 13 is fitted a' carbon rod ll which functions as an electrode. The carbon rod I4 is flat at both ends,

.ductor 23 attached to the ring It passes.

the upper end terminating at the upper end of the tube l3 and the lower end extending below the lower end of the tube.

To the cup l0 and the rod H, which form the two electrodes of the crucible, are attached contact rings or hands l5 and 16 formed of copper or other suitable conducting material. The band I5 is attached to the central portion of the cup and the band It is attached to the rod [4 adjacent its lower extremity.

By means of a yoke l1 formed of conducting material, a conducting support rod i8 is attached to the band IS, the rod projecting through a centrally drilled nut 8 which is screwed into a handle 19 formed of insulating material.

The handle is provided with a central passage 20 to accommodate a conductor 2| which is attached to the support rod l8 and which leads to a source of power, and is also provided with a second tubular passage 22 through which a con- The tubular passage 22 leads into the passage 20 and both wires are brought through a centrally drilled nut 24, screwed into the outer end of the handle, and connected to the secondary coil 25 of a transformer 28.

The primary coil 21 of the transformer 26 is connected through conductors 29 and 30 to the plug 3| which may be connected to a source of power.

Metals to be melted are placed in the semispherical concavity I I in cup II), where they complete the normally open secondary circuit through the cup and the central rod [4 to establish a current flow which will melt the metal, as will be understood without further discussion.

Having, thus described our invention, what we claim asnew and wish to secure by Letters Patent 1. An electric crucible comprising a tubular outer electrode provided with an internally concavedsurface extending from the outer to the inner surfaces of its cylindrical wall, an inner electrode provided with an insulating sheath fitted within said outer electrode and terminating at one end at the intersection of the concave surface with the inner wall of said outer electrode to form the floor and side wall of a receptacle in which material to be melted conductively bridges said electrodes, a manipulating means and conductors connecting said electrodes with a source of power.

2. An electric crucible comprising a tubular outer electrode provided with an internally concaved surface having its center of curvature in the central axis or the tube, means for closing the tube at the intersection of said concave suriace with the inner wall thereof to tom the floor and circular side wall of a cup-shaped receptacle for material to be melted, said means comprising a cylindrical inner electrode provided with a cylindrical insulating sheath and fitted within said outer electrode and extending exteriorly thereto, a supporting means and conductors connectin said electrodes with a source or power.

3. An electric crucible comprising a tubular outer electrode having its wall circularly concaved at one end thereof with the center of curvature in the central line 0! the tube, means for closing said tube at the intersection of the concave surface with the inner surface thereof to complete the floor and side wall of a cupshaped receptacle for the material to be melted, said means comprising a cylindrical inner electrode surrounded by a tubular sheath of insulating material, said inner electrode extendin beyond the outer electrode, an insulating handle, provided with longitudinal passages, attached to said outer electrode. and conductors connected to said electrodes and passing through said pas-- sages to a source oi power.

, 4. An electric crucible comprising an outer electrode formed of non-fusible conducting material and provided with a melting chamber adapted to contain the material to be melted, said chamber including a floor portion, an inner electrode also formed of non-fusible conducting material disposed partially within and centrally of the outer electrode in insulated relation with respect thereto, one end or said inner electrode terminating flush with and forming a continuation of said floor portion, conducting bands attached to said inner and outer electrodes, a handle provided with longitudinal passages, means including a supporting rod for connecting the band, attached to said outer electrode, to said handle, and conductors passing through said passages for connecting said rod and the band attached to said inner electrode with a source of power.

LAWRENCE F. BLACK.

CLARENCE H. MELLOR. 

